The present invention relates to a new and improved firing circuit, for use in an anti-disturbance explosive mine, for example. An anti-disturbance mine is one that is provided with some means for exploding the mine when it is disturbed, for example by enemy personnel in attempting to move or re-use the mine. Such exploding means are usually mechanical or chemical, rather than electrical in nature.
The present invention provides an electrical firing circuit which can be harmlessly activated by a suitable voltage source, by means of wires from a remote location, for example, but adapted to be quickly and reliably fired or triggered by: (1) sudden loss of voltage, due to breaking or otherwise disconnecting one or more voltage leads; (2) short-circuiting of the supply voltage terminals; (3) too rapid a decrease of the voltage supply; or (4) too high a supply voltage applied.
This firing circuit comprises a direct current voltage source or battery connected to a network comprising: a series combination of an SCR and an electrical detonator connected in parallel with a capacitor and a resistor and in series with another resistor, the voltage source and diode, in such manner that the SCR is connected to a point in the circuit having a normal potential lower than the cathode of the SCR. Preferably, this point is the junction of two series resistors connected across the voltage source, so that the gate potential is greater than zero.